The present invention relates generally to a safety apparatus which moves along a cable and serves as a support for a safety line or the like, and more particularly, to an improved fall arrest bypass device which may ride freely on a flexible and/or rigid cable without being impeded by cable supports intervally located along the cable.
Workers who perform tasks at heights on elevated or suspended platforms, and workers who operate near vertical edges need to be protected from falls that could cause injury or death. In fact, the U.S. government has established the Occupational Safety and Health Administration (xe2x80x9cOSHAxe2x80x9d) to regulate employers having workers who perform job tasks in these types of environments. Under regulations enacted by OSHA, each employee must be protected by a safety system when walking or working on a surface higher than six feet above the ground or a lower level.
This safety system may be a fall arrest system which arrests an employee in a short distance following a fall from a working level. A conventional fall arrest system consists of an anchorage point, a harness, and a mechanism connecting the harness to the anchorage point. It may also include a lanyard, deceleration device, lifeline, or suitable combination of these elements. A personal fall arrest system must limit the maximum arresting force on an employee to 1800 pounds, and be rigged so that an employee cannot fall more than six feet or come in to contact with any lower level. The fall arrest system must also be constructed to have sufficient strength to withstand twice the potential impact energy of a free-fall of six feet or the stopping distance provided by the system, whichever is less.
Fall arrest systems which are presently in use are typically attached to a single fixed anchor point. A worker is connected to the fixed anchor point by a lanyard attached to a harness or safety belt worn by the worker. This single fixed anchor system is a safe option for performing tasks in a limited area, but many tasks require the worker to move over a larger area. In the latter situation, the worker must disconnect the lanyard from the fixed anchor point and reconnect it to another fixed anchor point. During the change-over time, the worker is in danger of falling, which could result in serious injury or death. As a result, the single fixed anchor point system severely limits the type of tasks a worker can safely and legally perform.
Other safety systems exist that provide more mobility than the single fixed anchor point system. For example, in a track system, a lanyard is attached at one end to the worker via a harness, and to a trolley, slide, or other movable component on the other end. The trolley, slide, or other movable component is adapted to move freely along a conventional track, which can be an I-beam, a metal or plastic rail, or a cable that is either supported at various points along a work path or is anchored safely at its two end points. The supports function to both hold the track in place and to support the weight of the trolley and one or more workers in the event of a fall. The track is usually directly overhead in relation to the worker""s position, and can curve around corners or incline at angles. Some tracks such as I-beams require permanent installation.
Tracks like that described above typically require numerous supports which present an obstacle to conventional track-type fall arrest devices. A worker using a conventional fall arrest device must disconnect the device from the track between each support. Again, this places the worker in danger of falling. Additionally, these devices create wear on the track as well as the fall arrest device itself, which may result in frequent and costly replacement of parts.
Many tasks could be made easier and would benefit from a hands free fall arrest device that can pass freely over or through the track supports unaided by human intervention and unimpeded by undue frictional orientation of passing components. Designs of track-traveling and fall arrest devices that permit movement of a device past a plurality of local track supports are known. U.S. Pat. No. 304,730, to High, describes a truck that rides upon a gas-pipe track to move a fire escape ladder around a building. The truck disclosed by the High patent has two independent yokes, each with a carrying wheel adapted for the track. A gate is located on the rear side of the truck, and is hinged to the truck with a fulcrum-pin to allow the truck to pass through brackets that support the track. The truck described by the High patent is bulky and heavy, which prevents its use as a fall arrest device. Furthermore, these types of trucks are expensive to manufacture due to the redundant components that may be necessary to support an off-balance fire escape ladder, but are not necessary to support workers or other objects.
U.S. Pat. No. 5,979,599, to Noles, describes another track-traveling apparatus that rides upon a cable safety track which is supported by a plurality of supports. Noles discloses a track-traveling element with a single pulley that can ride upon the cable safety track. The track-traveling element has a slot which allows the element to pass over the brackets which support the cable. However, the track-traveling element disclosed by Noles cannot be removed from the cable safety track without severing the track or disengaging the track from its source. The permanence of the track-traveling element will cause it to be exposed to environmental conditions that could cause wear and corrosion, and prevents the track-traveling element from being easily removed and stored for later use.
To overcome the problems and disadvantages associated with the prior art, it is an objective of the improved bypass device of the present invention that it be strong enough to withstand the force of a falling object connected to the device. Furthermore, the bypass device should also be attached to a cable in a manner sufficient to hold a worker in case of a fall.
It is another objective that the improved bypass device of the present invention be capable of riding freely along a cable and passing over one or more support brackets without having to be removed from the track. The bypass device should also be able to ride freely around corners and curves of the track without having to be removed.
It is a further objective that the improved bypass device of the present invention be securely attached to the cable to prevent accidental disengagement that would place the worker in a dangerous situation. However, the improved bypass device of the present invention should also have a mechanism to easily remove it from the track so that the bypass device may be stored when not in use.
Another objective of the bypass device of the present invention is that it be lightweight with easily replaceable parts, and that it can be adapted to fit different size cables. The bypass device should ride freely on the cable without encountering significant friction, thereby preventing wear on the bypass device itself, as well as preventing the bypass device from causing any degree of wear to the support cable.
Finally, it is also an objective of the improved bypass device of the present invention that all of the aforesaid advantages and objectives be achieved without incurring any substantial relative disadvantage.
The disadvantages and limitations of the background art discussed above are overcome by the improved fall arrest bypass device which is taught by the present invention.
The bypass device is a component of a safety system which will meet and exceed applicable standards the government (OSHA) requires to protect workers having job duties at hazardous heights. The bypass device is attached at one end to a cable, and at the other end to a safety line extending to a harness of a worker. The safety line can be a rope lanyard, a retractable cable, webbing, or other types of lines known by those skilled in the art. The cable is engineered to support one or more workers in the event of a fall, and can be made from steel, nylon, polyester, or other well-known materials.
The cable should be held by supports located approximately every 20 feet to about 200 feet along the length of the cable, depending on the ground clearance and the flexibility of the cable used. The supports can hold the cable in a straight line, or, alternatively, the supports can be curved to wrap the cable around corners and over ledges. Each support may be mounted to the exterior of a building or rooftop along the work path, or, alternatively, the supports can be mounted upon poles along the work path. The supports are typically mounted by a mechanical securing device such as a bolt or other threaded fastener, or attached or mounted in other well-known ways including welding so that the supports can withstand the force exerted on the cable in the event one or more workers fall.
The bypass device connects the worker to the cable and is pulled along the cable and over the supports as the worker travels along the work path. The bypass device includes a frame member with a C-shaped body with two legs and an arm that extends downwardly from the base of the C-shaped body. The two legs surround a pulley located in a space therebetween. The pulley is grooved to fit in a mating relationship with the cable, and the pulley rotates around a pulley shaft with the assistance of a bearing so that it rides on the cable and over the supports with little friction. It would be apparent to one of skill in the art that the size and shape of the pulley will vary depending on the size of the cable and supports.
To attach the bypass device to the cable, the worker passes the cable through an opening to the interior space of the C-shaped body of the frame member. The opening is greater. than the cross-sectional diameter of the cable or section of the support holding the cable so as to allow the bypass device to pass onto the cable and support. Additionally, the opening permits the bypass device to pass over and through the supports when pulled along the cable.
To ensure that the bypass device remains engaged to the cable during use, a removable entry gate is attached to the frame member proximate the opening. The removable entry gate can either be attached to the arm of the frame member below the opening, or to one of the legs of the C-shaped body superior the opening. The gate reduces the size of the opening but does not close the opening completely. As a result, the opening is. made smaller than the cross-sectional diameter of the cable and supports and will prevent accidental disengagement during use. However, the partial opening is wide enough to allow a worker to pull the bypass device over the supports without having to detach the bypass device at each support.
The removable entry gate can be in a variety of shapes and sizes. For example, in one embodiment of the present invention, the removable entry gate is a single, substantially rectangular gate that partially blocks the opening to the interior of the body. Another embodiment may include two separate removable entry gates, each of which partially block the opening to ensure that the bypass device does not become disengaged from the cable. Because one of the purposes of the removable entry gate is to ensure that the bypass device remains engaged with the cable or supports, while allowing the bypass device to pass over the supports, one skilled in the art would realize that any imaginable embodiment of such a gate will fall within the scope of the present invention.
Once the removable entry gate is attached to the frame member, the worker is secured to the cable by the safety line attached to the arm of the frame member. The safety line may be attached to the arm directly by a latch, lockable D-ring, snap lock, or carabiner, or it may also be attached to a connector independently attached to the arm. The connector can be either a ring or swivel with a ring for attachment to the safety line. A swivel may allow for more mobility and a greater range of motion, however, it is not necessary for operation and use of the present invention.
Thus, it may be seen that the improved bypass device of the present invention overcomes the problems and disadvantages associated with the prior art by providing the aforesaid characteristics. The improved bypass device is strong enough to withstand the force of a falling object attached to the bypass device. Furthermore, the bypass device is removably attachable to a cable in a manner sufficient to hold a worker in case of a fall. The improved bypass device of the present invention also rides freely along a cable and can pass over support brackets, straight or curved, without having to be removed from the cable.
Furthermore, the improved bypass device of the present invention will remain engaged with the cable by its innovative use of a removable entry gate that prevents the bypass device from becoming disengaged from the cable, which would prevent a worker from being placed in a dangerous situation. This removable entry gate can also be easily removed so that the bypass device can be stored when not in use.
The bypass device of the present invention is also lightweight, with easily replaceable parts that can be adapted to fit cables of different size. The pulley of the bypass device allows the bypass device to ride freely on the cable without significant friction to prevent wear on the bypass device itself and prevent the bypass device from causing the cable to wear.
Finally, all of the aforesaid advantages and objectives are achieved without incurring any substantial relative disadvantage.
The above brief description sets forth rather broadly the more important features of the present invention so that the detailed description that follows may be better understood, and so that the present contributions to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter, which will form the subject matter of the invention. In this respect, before explaining an embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements set forth in the following description or illustrated in the drawings. The present invention is capable of other embodiments and of being practiced and carried out in various ways, as will be appreciated by those skilled in the art. Also, it is to be understood that the phraseology and terminology employed herein are for description and not limitation.